While PCBs are semivolatile and commonly measured in air throughout the globe, atmospheric sources[unreadable] of PCBs are almost completely undefined. This project will expand the knowledge of the sources and[unreadable] distribution of PCBs in air through a major field study coupled with atmospheric modeling. The study is[unreadable] structured as four aims: Under Aim 1 we will determine the prevalence and distribution of atmospheric PCBs[unreadable] in an urban area. We will monitor PCBs in air at select residential areas of Chicago, Illinois and East[unreadable] Chicago, Indiana and compare results to Columbus Junction, Iowa. Aim 1 will involve innovative methods in[unreadable] sampling design, including high volume sampling from parked health clinic vans and passive sampling at[unreadable] homes and schools. Over 1,000 air samples will be collected and analyzed for the full suite of PCB[unreadable] congeners each year. The logistics of air sampling will be accomplished by cooperating with local health[unreadable] agencies, schools, and governments. PCB congener analysis will be supported by a fully automated[unreadable] analytical method for atmospheric PCB extraction, concentration, cleanup, analysis, and quality assurance.[unreadable] Project Aims 2-4 focus on characterizing the sources using additional field measurements coupled with[unreadable] mathematical modeling. Aim 2 involves characterization of PCBs released from contaminated water. A field[unreadable] and modeling study will examine the water of Indiana Harbor / Shipping Canal in East Chicago as an[unreadable] emission source of PCBs. Aim 3 concerns characterization of PCBs released from the soils of a former[unreadable] refinery site destined to store PCB contaminated sediments. Under Aim 4 we will evaluate mechanistic[unreadable] models, dispersion models, and other computational models for estimating PCB emissions from other[unreadable] (unknown) sources in the Chicago / East Chicago urban industrial region. Aims 2-4 include considerations[unreadable] of the effects of season, local meteorology, topography, re-suspension of contaminated sediment,[unreadable] construction activities at a contaminated site, and regional dispersion.